Wire gripping elements and method of making and crimping same



1962 H. BATCHELLER 3,051,773

WIRE GRIP? ELEMENTS AND HOD 0F MAKING AND CRIMPING SA Filed Sept. 23,1959 United States Patent 3,051,773 WIRE GRIPPING ELEMENTS AND METHOD OFMAKING AND CRIMPING SAME Hugh W. Batcheller, Newton Highlands, Mass.(188 Needham St., Newton Upper Falls, Mass.) Filed Sept. 23, 1959, Ser.No. 841,865 4 Claims. (Cl. 174-94) This invention relates towire-gripping elements of an electric connector or other object to besecured to the Wire and a method of making and crimping the same. It haslong been the practice to provide opposing tongues of metal to be curledabout the end portion of a wire and crimped into the form of a tubularferrule. Owing to the natural resilience of the metalwhich is usuallybrassthere is always a slight tendency on the part of the curled tonguesto relax a bit, this tendency being more pronounced when the tongues aremade of the lighter gauges of metal. It is important for a goodelectrical connection that a strong interfacial pressure he maintainedbetween the surfaces of the wire and the ferrule which are in mutualcontact. According to the invention, this high degree of interfacialpressure is maintained by interlocking the ends of the tongues of metalwhich are crimped around the wire to form the wiregripping ferrule. Theinterlock is formed by providing in the end of one tongue a recess whichis wider at its inner end than at the extremity of the tongue, and aprojection on the end of the other tongue which is wider at itsextremity than at its junction with the body of the tongue. In thecrimping operation the projection is made to enter the recess endwisewhereupon the end portions of both tongues are struck with suiiicientforce to flatten the metal considerably and to cause it to flow1aterally to fill the spaces between the edges of the recess in onetongue and the edges of the projection at the end of the other tongue.The result is a positive interlock which does not yield or relax, thewide extremity of the projection being thus swaged to fill the wideinner end of the recess.

For a more complete understanding of the invention reference may be hadto the following description thereof, and to the drawing, of which-FIGURE 1 is a perspective view of an electric connector member mountedon the end portion of an insulated wire, said member having awire-gripping ferrule embodying the invention;

FIGURE 2 is a perspective view of the connector member shown in FIGURE 1prior to being mounted on a wire;

FIGURE 3 is a side elevation of the member mounted on a wire;

FIGURE 4 is a sectional view of a die and anvil, the latter havingthereon a connector member ready to be crimped about a wire, the sectionof the member being on the line 4-4 of FIGURE 3;

FIGURES 5 and 6 are sections similar to FIGURE 4 but show the parts insuccessive stages of operation;

FIGURE 7 is a fragmentary plan view of the end portions of the tonguesforming the ferrule, prior to swaging, seen as indicated by the line 77of FIG- URE 5;

FIGURE 8 is a fragmentary plan view as indicated by the line 88 ofFIGURE 6, showing the interlocked ends of the ferrule tongues afterbeing swaged;

FIGURE 9 is an enlarged fragmentary sectional view on the line 99 ofFIGURE 8;

FIGURES 10 and 11 are fragmentary plan views, similar to FIGURE 7, ofmodified forms of interlocking ferrules.

FIGURE 1 illustrates a member of an electric connector which is attachedto an insulated wire 22. The

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member 20 is made of sheet metal, usually soft brass, and has wiregripping elements consisting of two tongues 24 and 26 which are wrappedaround the bared end portion 28 of the insulated wire. The wire grippingportion of the connector member also has a pair of tongues 30 and 32which are to be wrapped around the insulation of the wire adjacent tothe bared end portion 28 as illustrated in FIGURE 1. It is importantthat when the tongues 24 and 26 are crimped around the wire portion 28,the wire portion be tightly and permanently squeezed so as to make agood electrical connection. A well designed crimping machine will crimptongues of the type similar to the tongues 30 and 32 tightly about awire, but when the presure of the crimping apparatus is released, thenatural resilience of the metal usually causes the tongues to relaxslightly. This reduces the interfacial pressure between the innersurfaces of the tongues and the surfaces of the wire itself. The chiefpurpose of the present invention is to provide interlocking means whichwill operate reliably in the crimping operation and will serve to holdthe tongues which are crimped about the wire permanently in tightlypressing engagement with the wire. For this purpose a recess is formedin the end of one of the tongues and a projection of approximately thesame shape as that of the recess is formed on the end of the othertongue. The recess is such a shape that the maximum width is at itsinner end, the maximum width of the projection on the other tongue beingat its extremity. In order to facilitate the crimping operation, themaximum width of the extremity of the projection is slightly less thanthe maximum width of the recess so that the projection can be insertedendwise in the recess by movement of the ends of the two tongues towardeach other in the same plane. One form of interlock is shown in FIGURE7, this consisting of a T-shaped recess 34 extending in from the end ofthe tongue 26, the portion of maximum Width of the recess being at itsinner end. The recess thus consists of a wide longitudinal slotextending in from the end of the tongue and having an inner portion ofgreater width which can be considered as the transverse portion of theT. The complemental element is a T-shaped projection 40 on the end ofthe tongue 24, this projection having a shape approximating that of therecess 24. The extremity of this projection is its widest part. Thisextremity is slightly less in width than the slot 36 of the recess 34 sothat it can enter endwise through the longitudinal slot 36 to theposition shown in FIGURE 7. The length of the projection 40 ispreferably equal to the length of the recess 34 so that when theprojection is inserted in the recess as shown in FIG- URE 7, the endedges of the two tongues will abut each other. This will leave narrowareas of clearance between the sides of the projection 40 and side edgesof the recess 34. When the two tongues have been brought together inabutting relationship, the projection 40 and the metal adjacent to therecess 34 are cold-forged or swaged to flatten these portions of thetongues (FIGURE 9) sufficiently to spread such metal laterally so as tofill the crevices between the projection 40 and the edges of the recess34 as indicated in FIGURE 8. This forms a positive interlock between theends of the tongues at the moment when the pressure of the tongues uponthe wire which the tongues surround is at its maximum. The wire grippingportion of the electric member consequently cannot relax but ispermanently held in tightly gripping relationship to the wire which itsurrounds.

Other shapes of interlock-s can be employed such as the keystone ordovetail shape illustrated in FIGURE 10 and the L-shape in FIGURE 1 1.In both of these cases the maximum width of the recess is at the innerend thereof. In FIGURES 4, 5 and 6 an anvil 50 and die 52 for thecrimping of the tongues about the wire are shown in suc- 3 cessive stepsof operation. The wire-gripping portion of the connector member 20 isplaced on the grooved top of the anvil 50, the tongues 24 and 26extending upward as shown to receive the end portion 28 of the wirebetween them. The die then descends as shown in FIGURE 5 to crimp thetongues into a cylindrical form, the projection 40 moving endwise intothe recess 34 until the end edges of the tongues meet as indicated inFIGURE 7. The die 52 then moves a little further downward to theposition shown in FIGURE 6. This has the etfect of imposing greatinterfacial pressure between the wire-gripping portion of the electricmember and swages the projection 40 and the end portion of the tongue 26adjacent to the recess 34 so as to complete the interlock as illustratedin FIGURE 8. This forms a permanently tight connection between theconnector member 29 and the wire which it grips.

I claim:

1. A method of joining together two metal strip ends, which comprisesforming a recess in one said end, said recess being widest at its innerend, forming a projection on the other said end approximately the sameshape as said recess and widest at its extremity, the widest part ofsaid projection being slightly narrower than the narrowest part of saidrecess, moving said ends edgewise into mutual engagement with theprojection within said recess, and cold-forging said projection and themetal adjacent to said recess by striking on the faces thereof toflatten and spread said projection and adjacent metal sufiiciently tofill the clearance between the edges of said projection and the edges ofsaid recess.

2. A method as described in claim 1, including the steps of making aT-shaped recess in one said end and a T-shaped projection on the othersaid end.

3. A method of crimping the wire-gripping portion of an electric elementabout a wire, which comprises shaping said wire-gripping portion in theform of two tongues with a recess in the end of one of said tongueswhich varies in width and is widest at its inner end and a pro jectionon the end of the other tongue which is shaped approximately like saidrecess but is narrow enough to enter said recess by movement in the sameplane, curling said tongues about said wire so that said projectionenters edgewise into said recess, and cold-forging said projection andthe metal adjacent to said recess by striking on the faces thereof toflatten and spread the same so as to close the clearance between theedges of the projection and the edges of the recess.

4. An electric element of sheet metal adapted to be mounted on the endportion of a wire, said element having a Wire-gripping portioncomprising oppositely extending tongues adapted to be curled around awire to grip the same, one of said tongues having a T-shaped recess inthe end thereof, said recess consisting of a slot extending in from theend of said tongue with a widened inner end, the other said tonguehaving a T-shaped projection extending out from the end thereof thelength of said recess being substantially equal to that of saidprojection, the maximum width of said projection being slightly lessthan the minimum width of the slot.

References Cited in the file of this patent UNITED STATES PATENTS1,417,039 Darrach May 23, 1922 1,999,818 McIntyre Apr. 30, 19352,283,918 Dekome May 26, 1942 2,317,198 Kasper Apr. 20, 1943 2,789,278Soreng Apr. 16, 1957 2,842,262 Wismer July 8, 1958 FOREIGN PATENTS 5,585reat Britain Mar. 17, 1894 516,640 Great Britain Ian. 8, 1940 1,133,887France Apr. 3, 1957

